You become a US tax resident under the substantial presence test when you spend 31+ days in the US in the current year and 183+ weighted days over three years — counting all of this year, one-third of last year, and one-sixth of the year before. Crossing this line changes far more than an LLC owner's filing form; it changes which country's tax system reaches their worldwide income.

Key facts

  • The test has two parts, both required: at least 31 days in the US during the current calendar year, and at least 183 weighted days across the current year and the two years before it (IRS: Substantial presence test).
  • The weighted count uses all current-year days, one-third of prior-year days, and one-sixth of the year-before-that's days.
  • Certain days don't count at all — most notably for exempt individuals (some students, teachers, and trainees on specific visas) and days present due to a medical condition that arose while in the US.
  • Meeting the test makes someone a US tax resident, filing Form 1040 and reporting worldwide income — not Form 1040-NR.
  • A closer-connection exception can, in limited cases, let someone who technically meets the day count still be treated as a non-resident.

The formula with a worked example

The weighted count works like this: take all the days present in the current year, add one-third of the days present in the prior year, add one-sixth of the days present in the year before that. If the total is 183 or more, and the current year alone had at least 31 days, the substantial presence test is met. Worked example: someone who spent 120 days in the US this year, 120 days last year, and 120 days the year before: 120 + (120 ÷ 3 = 40) + (120 ÷ 6 = 20) = 180 weighted days — just under the 183-day line, so the test is not met at that pace. Add even a modest increase in current-year days and the same person could cross it, which is exactly why LLC owners who travel to the US periodically for business need to actually count, not estimate.

Days that don't count

Not every day physically present in the US counts toward either half of the test. The most relevant exclusions for a foreign LLC owner:

  • Exempt individual status — certain visa categories (some students, teachers, trainees, and foreign government-related individuals) have their days excluded for a defined period, regardless of how much time they actually spend in the US.
  • Medical condition days — days a person is unable to leave the US because of a medical condition that arose while they were present don't count, provided the condition genuinely prevented departure.
  • Regular commuters from Canada or Mexico for employment, and individuals in transit between two foreign points, have specific narrow carve-outs as well.

These exclusions are narrow and fact-specific — they're not a general "business travel doesn't count" rule, so an LLC owner who spends meaningful time in the US for ordinary business reasons should assume those days count unless a specific exclusion clearly applies.

What residency changes

Crossing the substantial presence test line is a significant shift, not a technicality:

  • Worldwide income becomes reportable on Form 1040, not just US-source or effectively connected income on Form 1040-NR.
  • FBAR obligations that may have applied only to the LLC now clearly extend to the individual's own personal foreign accounts as well, if thresholds are met.
  • Filing status options, standard deduction, and various elections change, since US resident and non-resident returns follow meaningfully different rules.

The LLC's own Form 5472 filing obligation is unaffected either way — that's tied to the LLC's foreign ownership, not the owner's personal residency status.

The closer-connection exception

Someone who meets the day-count test but was present under 183 days in the current year specifically, maintains a tax home in a foreign country, and has a closer connection to that foreign country than to the US, may be able to claim the closer-connection exception and still be treated as a non-resident for the year. This is a specific, narrower carve-out than the general substantial presence rules, has its own filing requirements (Form 8840), and isn't available to someone who has already applied for or holds a green card. It's a genuine planning lever for LLC owners who travel to the US moderately, not an automatic fallback.

Planning around the line

For an LLC owner who travels to the US periodically — client visits, conferences, checking in on US operations — the practical takeaway is simple: track actual days present, don't estimate from memory, and check the running weighted total before assuming another trip is safe. A pattern of travel that felt casual in year one can quietly approach the 183-day weighted threshold by year three, especially since roughly a third of last year's days and a sixth of the year before are still counting against the current total.

Frequently asked questions

Do days spent in the US on a B-1/B-2 visitor visa count toward the substantial presence test? Generally yes — ordinary business or tourist visits on a B-1/B-2 visa count as days present unless a specific narrow exclusion (like the medical-condition exception) applies. There is no general exclusion for time spent on a visitor visa specifically.

Does a tax treaty override the substantial presence test? Not automatically — many treaties include a tiebreaker provision that can determine residency when someone would otherwise be considered a resident of both countries, but that's a treaty-specific claim made on a return, not something that changes the substantial presence test's own mechanics.

Is the substantial presence test the same as the green card test? No. The green card test makes someone a US resident based on holding lawful permanent resident status, regardless of days present, while the substantial presence test is based purely on physical presence. Either one independently can make someone a US tax resident.

Are day-counting apps reliable for tracking this? They can help as a starting log, but the underlying data — actual entry and exit dates — should be verified against travel records (passport stamps, boarding passes, entry/exit records) rather than trusted blindly, especially once someone is close to the threshold and the stakes of miscounting are real.

Written by Ifetoluwase Samuel Pirisola, Managing Director of Caldwell Tax Services, LLC — July 2026. General information, not tax advice for your specific situation — day counts and the closer-connection exception both depend on your specific travel history. Start your intake if you travel to the US regularly and want your day count reviewed before it becomes a problem.

Sources: IRS: Substantial presence test · FinCEN: Report of Foreign Bank and Financial Accounts · Form 1040-NR for LLC owners · Glossary